Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Citrus reticulata Blanco; Citrus nobilis, Citrus reshni, Mandarin orange, tangerine, clementine, Satsuma orange

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

y

1.02

Has the species become naturalized where grown?

y=-1, n=-1

n

1.03

Does the species have weedy races?

y=-1, n=-1

n

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

2

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

y

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

n

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

n

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

n

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

n

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

n

4.01

Produces spines, thorns or burrs

y=1, n=0

y

4.02

Allelopathic

y=1, n=0

n

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

y

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

y

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

n

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

y

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

n

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

n

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

y

6.04

Self-compatible or apomictic

y=1, n=-1

y

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

4

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

n

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

y

7.04

Propagules adapted to wind dispersal

y=1, n=-1

n

7.05

Propagules water dispersed

y=1, n=-1

n

7.06

Propagules bird dispersed

y=1, n=-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

7.08

Propagules survive passage through the gut

y=1, n=-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

n

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

n

8.03

Well controlled by herbicides

y=-1, n=1

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

y

Total score:

-5

Notes

Source

1.01

Citrus fruits are native to southern China and Southeast Asia where they have been cultivated for some 4,000 years. Mandarins from southern China were brought to Europe and the Americas in the 1800's. The satsuma mandarin originated in Japan more than 400 years ago. There are some 100 varieties of satsumas in Japan, about a dozen of which have been released in the United States.

http://www.floridata.com/ref/C/citr_ret.cfm

1.02

no evidence

1.03

no evidence

2.01

Distributional range: widely cultivated in tropics & subtropics, probable origin s.e. Asia

http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl?Citrus+reticulata

2.02

2.03

(1) "Hardiness: USDA Zones 8B - 11. Mature satsumas and 'Changsha' tangerines can tolerate temperatures as low as 15ºF (-9.4ºC) or lower if they have become cold-acclimated. A sudden freeze to 25ºF (-3.9ºC)without any previous cold weather can be more damaging than a freeze to 20ºF (-6.7ºC) that comes after a period of low temperatures. Freeze damaged mandarins may lose some leaves, but they usually recover."
(2) Mandarins are grown throughout the main citrus belt between 45°N and 35°S. (3) 0-2300 m, tropical wet & dry (Aw), steppe or semiarid (Bs), subtropical humid (Cf), subtropical dry summer (Cs), subtropical dry winter (Cw), More cold hardy than other citrus fruit species. There are however cultivars that can be grown in wet tropical lowlands. The tree is drought-resistant.

(2) Sumeru Ashari, 2003. Citrus reticulata Blanco. [Internet] Record number 1494 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Monday, 17 May 2004. (3)http://ecocrop.fao.org/

2.04

Distributional range: widely cultivated in tropics & subtropics, probable origin s.e. Asia

http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl?Citrus+reticulata

2.05

Origin and geographic distribution Mandarin constitutes one of the three most strongly differentiated species in the genus. Prior to its distribution, selection and hybridization by man, the mandarin would have been limited to South-East Asia, including the Malesian Archipelago. Some writers specify Indo-China as the area of origin, but this is not likely to have been more than the core of the original range. Of the mandarin groups distinguished in the trade, the Satsuma mandarins originated in Japan, the King mandarins in Indo-China, the Mediterranean mandarins in Italy, and the common mandarins in the Philippines. At present mandarins are widely cultivated in all tropical and subtropical regions of the world.

Sumeru Ashari, 2003. Citrus reticulata Blanco. [Internet] Record number 1494 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Tuesday, 11 May 2004.

3.01

no evidence

3.02

no evidence

3.03

no evidence [variety ushu is a quarantine plant due to pests]

http://drpsp.clemson.edu/dpi/npp.htm

3.04

no evidence

3.05

no evidence

4.01

"small, sometimes spiny, trees with slender branches"

http://www.floridata.com/ref/C/citr_ret.cfm

4.02

no evidence

4.03

no evidence

4.04

not a fodder plant

http://ecocrop.fao.org/

4.05

no evidence

4.06

AB: "A survey was undertaken to determine the food plant range and preference, and distribution of Anoplophora versteegii in Assam, India, during January-March 1984-87. Mandarin, lemon, Citrus jambhiri, C. limonia, C. limettioides, sour orange, pummelo and citron were attacked by A. versteegii, with mandarin and C. jambhiri being preferred. No other horticultural, silvicultural or plantation trees were attacked by the cerambycid."

Phukam, E. Khound, J. N. Dutta, S. K. (1993) Survey for host range of Citrus trunk borer, Anoplophora versteegi (Ritsema) (Coleoptera: Cerambycidae) in Assam. Indian Journal of Entomology, 1993, Vol. 55, No. 1, pp. 34-37, 10 refs.

4.07

no evidence

4.08

"It is in leaf all year. "

http://www.scs.leeds.ac.uk/cgi-bin/pfaf/arr_html?Citrus+reticulata&CAN=COMIND

4.09

(1) Light: Full sun to partial shade. (2) "It cannot grow in the shade. " (3) It tolerates some shade

(1) http://www.floridata.com/ref/C/citr_ret.cfm (2) http://www.scs.leeds.ac.uk/cgi-bin/pfaf/arr_html?Citrus+reticulata&CAN=COMIND (3)http://aggie-horticulture.tamu.edu/plantanswers/fruit/satsuma.html

4.1

Soil tolerances: clay; loam; sand; slightly alkaline; acidic; well-drained

http://hort.ifas.ufl.edu/trees/CITSPPA.pdf

4.11

"small, sometimes spiny, trees with slender branches"

http://www.floridata.com/ref/C/citr_ret.cfm

4.12

no evidence

5.01

terrestrial

5.02

small tree; Rutaceae

5.03

small tree; Rutaceae

5.04

tree

6.01

no evidence

6.02

"Germination usually takes place within 2 - 3 weeks at 13°c."

http://www.scs.leeds.ac.uk/cgi-bin/pfaf/arr_html?Citrus+reticulata&CAN=COMIND

6.03

RAPD analysis on 5 cultivars of citrus showed that in the amplification bands of OP46 primer, Huyou had 6 bands similar to pummelo's and tangerine's and had 4 bands similar to those of orange. Combining RAPD analysis with characteristics and cold resistance analysis, it can be inferred that Huyou is a polyhybrid from repeated natural hybridizations of pummelo, tangerine and orange.

Chen LiGeng Hu XiQin Zhao SiQing (2002) Molecular research on Huyou origin. Acta Horticulturae Sinica, 2002, Vol. 29, No. 3, pp. 276-277, 4 ref.

6.04

(1) 'Clementine' comprises sexual, freely crossable clones as well as self-incompatible clones. (2)The plant is self-fertile

(1) Sumeru Ashari, 2003. Citrus reticulata Blanco. [Internet] Record number 1494 from TEXTFILE On-line. Verheij, E.W.M. and Coronel, R.E. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Tuesday, 11 May 2004. (2)http://www.scs.leeds.ac.uk/cgi-bin/pfaf/arr_html?Citrus+reticulata&CAN=LATIND

6.05

"The white flowers appear in March and April and are very fragrant, usually attracting hoards of honey bees."

http://www.floridata.com/ref/C/citr_ret.cfm

6.06

no evidence

6.07

(1)Trees come into bearing in the second or third year [plants from air layering] (3)First fruits may be harvested after 2-8 years [the higher end of range is for seedlings]

(1)http://www.floridata.com/ref/C/citr_ret.cfm (2)http://ecocrop.fao.org/

7.01

unlikely, fleshy fruit with relatively large seeds

7.02

Distributional range: widely cultivated in tropics & subtropics, probable origin s.e. Asia

http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl?Citrus+reticulata

7.03

people discard seeds after eating fruit

7.04

unlikely, fleshy fruit with relatively large seeds

7.05

no evidence

7.06

(1) "Fruit samples were harvested at 14-day intervals in each harvesting season, beginning shortly before commercial harvest and ending at the time when severe abscission or severe bird invasion occurred. " [fruit used by birds -- pecked -- no evidence that large central seeds are consumed]
(2) The effectiveness of balloons with eyespot patterns in discouraging boat-tailed grackles (Quiscalus major) from using a simulated orange grove (magnolia trees with orange fruits attached) was investigated in a series of 4-day trials. The mean distance to the trees of 6-bird experimental flocks was the same with a plain white balloon present as with no balloon. A white balloon with red and black eyespots kept birds at a greater distance from the trees throughout the trial. A black balloon with orange and yellow eyespots did not repel the birds. Observations of birds using the area within 1 m of the trees revealed no effect from eyespot balloons nor was the number of oranges pecked reduced in the presence of such balloon

(1) Liu, F. W. Wang, T. T. Pan, C. H. (1998) Maturity characteristics of 'Ponkan' mandarin (Citrus reticulata Blanco), Tankan (C. tankan Hayata) and 'Liucheng' orange (C. sinensis Osbeck) in harvesting seasons. Journal of the Chinese Society for Horticultural Science, 1998, Vol. 44, No. 3, pp. 265-274, 8 ref.
(2) Avery, M. L., D. E. Daneke, D. G. Decker, P. W. Lefebvre, R. E. Matteson, and C. O. Nelms. 1988. Flight pen evaluation of eyespot ballons to protect citrus from bird depredations. Pages 277-280 in Proceedings, Thirteenth Vertebrate Pest Conference, Monterey, California. University of California, Davis, USA.

7.07

no evidence of any means od attchment

7.08

probably damaged by digestion, but seeds are smaller than other citrus spp.

8.01

Seeds were collected from eighteen plants of mandarin (Citrus reticulata). The number of seeds per fruit varied between 9.6 and 20.4. [large fruit with few seeds]

Das, A. Mandal, B. Paul, A. K. Chaudhuri, S. (2003) Standardization of germination for increased production of nucellar plantlets of mandarin orange (Citrus reticulata Blanco) under controlled condition. Journal of Interacademicia, 2003, Vol. 7, No. 3, pp. 343-346, 4 ref.

8.02

(1)"Seeds of mandarin cv. Coorg Orange were stored in open containers under ambient conditions (16-35 deg C and 40-70% relative humidity). After four days of storage, significant reductions in seed germination percentage (from 95 to 45%) and seed moisture content (from 50.9 to 6.0%) were observed. The increase in storage duration resulted in the reduction of seedling vigour and dehydrogenase [oxidoreductase] activity in seeds, and in the increase in electrical conductivity and soluble sugar content of seed leachates." (2)mandarin (C. reticulata) seeds were intolerant of desiccation and showed recalcitrant storage behaviour.

(1)Doijode, S. D. (2003) Changes in viability, vigour and solute leakage during storage of mandarin (Citrus reticulata Blanco) seeds. Seed Research, 2003, Vol. 31, No. 1, pp. 77-79, 12 ref. (2)Khan, M. M., K. Thompson, M. Usman, and B. Fatima. 2002. Role of moisture content and controlled atmosphere in <i>Citrus</i> seed storage. International Journal of Agriculture and Biology 4:259-266.

8.03

no evidence of being controled

8.04

(1) "Plants dislike root disturbance and so should be placed into their permanent positions when young. " [vulnerable surface root system] (2)Skeleton pruning (on the left) can rejuvenate some citrus trees into completely new growth.[this is very intense prunning to remove almost all leaves] (3)Mandarins have shapely, symmetrical, rather open, rounded crowns and rarely require pruning.

(1)http://gardenbed.com/source/18/1741_cul.asp (2)http://www.ricecrc.org/reader/cit-growing/h217.htm (3)http://www.floridata.com/ref/c/citr_ret.cfm

8.05

(1) "In Hawaii, heavy infestations of the whitefly have been observed on the foliage of various citrus trees such as pummelo, lemon, and orange. Damage. The greatest injury is caused by the sucking of plant sap, which removes water and nutrients. Additional damage is caused by the excretion of tiny droplets of sticky honeydew from the whitefly upon which grows sooty mold fungus, usually on the upper surfaces of leaves. A heavy growth of sooty mold on leaves results in reduced respiration and photosynthesis. The combination of direct feeding of high numbers of whiteflies with large amounts of sooty mold growth being produced causes a decline in the general health of the tree and a reduction in fruiting." [domesticated Citrus trees require human protection from insects] (2)Phytophthora foot rot appeared in the Azores in 1842 and later in other parts of the world, which stimulated a search for resistant stocks. [Tangerine is not listed as a resistant root stock - they are typically grafted]

(1)http://www.hawaiiag.org/hdoa/npa/npa99-03_citrusbf.pdf (2)http://www.uga.edu/fruit/citrus.htm